<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        h2{
            color: blue;text-decoration: line-through;
        }
    </style>
</head>
<body>
    <!-- 选择器选中要更改的元素，进行更改 -->
    <!-- 外部引用：引用外部css文件,优先考虑 -->
    <link rel="stylesheet" href="./style.css">
    <h1>早上好</h1>
    <!-- 内部引用 -->
    
    <h2>早上好</h2>
    <!-- 内联：优先级高，更改困难，不优先考虑 -->
    <h3 style="color: aquamarine;text-decoration: overline;">早上好</h3>
</body>
</html>